Speed sensor : Sensor « Hardware « Android

1. Android
2. Hardware
3. Sensor

Speed sensor

   


package app.test;

import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;

import android.app.Activity;
import android.content.Context;
import android.hardware.SensorListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;

public class Test extends Activity {
  Handler handler = new Handler();
  SensorManager sensorManager;
  TextView myTextView;
  float appliedAcceleration = 0;
  float currentAcceleration = 0;
  float velocity = 0;
  Date lastUpdate;

  @Override
  public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.main);

    myTextView = (TextView) findViewById(R.id.myTextView);
    lastUpdate = new Date(System.currentTimeMillis());

    sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    sensorManager.registerListener(sensorListener,
        SensorManager.SENSOR_ACCELEROMETER,
        SensorManager.SENSOR_DELAY_FASTEST);

    Timer updateTimer = new Timer("velocityUpdate");
    updateTimer.scheduleAtFixedRate(new TimerTask() {
      public void run() {
        updateGUI();
      }
    }, 0, 1000);
  }

  private void updateGUI() {
    handler.post(new Runnable() {
      public void run() {
        myTextView.setText(velocity + "");
      }
    });
  }

  private void updateVelocity() {
    Date timeNow = new Date(System.currentTimeMillis());
    long timeDelta = timeNow.getTime() - lastUpdate.getTime();
    lastUpdate.setTime(timeNow.getTime());

    float deltaVelocity = appliedAcceleration * (timeDelta / 1000);
    appliedAcceleration = currentAcceleration;

    velocity += deltaVelocity;
  }

  private final SensorListener sensorListener = new SensorListener() {

    double calibration = Double.NaN;

    public void onSensorChanged(int sensor, float[] values) {
      double x = values[SensorManager.DATA_X];
      double y = values[SensorManager.DATA_Y];
      double z = values[SensorManager.DATA_Z];

      double a = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2)
          + Math.pow(z, 2));

      if (calibration == Double.NaN)
        calibration = a;
      else {
        updateVelocity();
        currentAcceleration = (float) a;
      }
    }

    public void onAccuracyChanged(int sensor, int accuracy) {
    }
  };
}

   
    
    
  

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